Testing-paper and method of making same.



UNITED STATES PATENT OFFICE.

KARL DlETERlCI-I, OF HELFENBERG, GERMANY.

TESTING-PAPER AND METHOD OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 691,249, dated January 14, 1902.

I Application filed May 23,1901. Serial No, 61,664. (No specimens.)

To all whom it may concern.-

Be it known that I, KARL DIETERIOH, a subject of the King of Saxony, residing at Helfenberg, near Dresden, Germany, have invented certain new and useful Improvements in Compound Ohemical-Testing Papers and Processes of Making the Same; and I do hereby declare the following to bea full, clear, and exact description of the invention, such as will enable others skilled in the'art to which it appertains to make and use the same.

This invention relates to chemical-testing paper, and has for its object to provide an improved compound testing-paper for testing difierent solutions, such as acids and alkalies, at one operation and an improved process for making such compound paper.

The need of a testing or litmus paper which is not alone sensitive, as the usual blue paper, to acidity or, as the usual red paper, to alkali, but which simultaneously reacts upon both the acid and alkali, has led to the manufacture of the so-called neutral reacting litmus-paper. This neutral paper bya certain neutralization of the color material in violetcolored manufactured paper has the disadvantage that it is not durable and is always uneven in its sensibility, being either excessively sensitive to acidity, or vice versa, to

alkali.

The object of this invention is to provide litmus-paper, as well as other test-papers, with all possible coloring and testing qualities, in which a plurality of sheets of the testing-papers are placed one beside the other, but separated from each other. This, however, is not easily possible, for instance, with red and blue litmus colors, because of the porosity of the paper,be it filtering or. writing paper, which allows the difierent solutions of coloring-matter to run into each other. Even when this should not be thecase at the beginning in storing up the paper a gradual exchange of colors through the various sheets of the paper would occur. In my invention this inconvenience is obviated by placing between the dilferent strips of coloring-paper a very narrow strip of a substance which renders the paper at this place impermeable to liquid solutions and, so to say, insulates the different strips of testing-papers.

This can or coatings of heated ceresin or any of the be-' fore-named substances, and between these insulating-strips alternate coatings of the different reacting color materials are applied. It is sufficient to apply the insulating mass and also the reacting material on one side only of the paper, as it penetrates sufficiently into the paper. Thus the red and blue coloring-matter of litmus can be placed parallel upon one paper, and in the same manner any desired acting body of animal or synthetic origin may be used. Also when the quantities of theacting bodies are varying narrow or wide strips of not only two, but several, acting bodies can be applied side by side, or on one sheet twenty to thirty strips of red litmus- .paper can be united with twenty to thirty strips of blue. In each case two or more reactions can be executed or tested at once by coating one piece of paper. The compound may also have strips of the ordinary testingpapers pasted upon it instead of being colored in strips, if so desired.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is-

1. A process of manufacturing testing-paper which is sensitive to two or more chemical substances by first providing the paper with narrow insulating strips or coatings of a substance impervious and as far as possible indifierent' to the chemicals to be tested, and thereafter applying the different testing substances in parallel, separated strips on the paper, substantially as described.

2. Acompound chemical-testing paper consisting of a sheet of paper having separated strips of testing coloring or material thereon,

separated by insulating-coatings on the paper, substantially as described.

3. A compound chemical-testing paper consisting of a sheet of paper having separated strips of testing coloring or material thereon, 'vious to acids and alkalies, substantially as 10 separated by insulating-coatings on the padescribed. per, the various strips of testing material be- In testimony whereof I affix my signature ing sensitive to diiferentohemicai substances, in presence of two Witnesses.

5 substantially as described.

4. Aoompoundchemieai-testingpaper con- KARL DIETERIOH sisting of a sheet of paper provided with ad- Witnesses: V jacent but separated strips of blue and red HERNANDO DE SOTO,

litmus coloring, separated by strips imper- PAUL AREAS. 

